Thanks for your question on Health Care Magic.
I can understand your mother's situation and problem.
By your history and description, possibility of
respiratory failure is more.
COPD patients tend to have type 2 respiratory failure. It is actually hypercarbic respiratory failure. In this patient fails to exhale carbon dioxide.
So excess carbon dioxide accumulate in the body and cause hypercarbia (high carbon dioxide).
High carbon dioxide causes sleepiness,
tiredness,
drowsiness, weakness etc.
So her symptoms are suggestive of hypercarbic respiratory failure more.
Possibility of
renal failure is less. In this patient develops anuria (no urine), edema face and lower limbs etc.
Best way to differentiate between respiratory and renal failure is by ABG (
arterial blood gas) analysis and renal function test.
Hope I have solved your query.
Wishing good health to your mother. Thanks.